Fix #1675: Emit __ldftn/__ldvirtftn pseudo expressions, if delegate construction is not supported.

ICSharpCode.Decompiler.Tests/ICSharpCode.Decompiler.Tests.csproj

@@ -82,6 +82,8 @@
     <Compile Include="TestCases\ILPretty\ConstantBlobs.cs" />
     <Compile Include="TestCases\Pretty\OutVariables.cs" />
     <Compile Include="TestCases\Pretty\CustomTaskType.cs" />
+    <None Include="TestCases\Ugly\NoExtensionMethods.Expected.cs" />
+    <Compile Include="TestCases\Ugly\NoExtensionMethods.cs" />
     <None Include="TestCases\VBPretty\VBCompoundAssign.cs" />
     <Compile Include="TestCases\Pretty\ThrowExpressions.cs" />
     <None Include="TestCases\ILPretty\Issue1145.cs" />

ICSharpCode.Decompiler.Tests/TestCases/Ugly/NoExtensionMethods.Expected.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Runtime.CompilerServices;
+
+[assembly: Extension]
+
+namespace ICSharpCode.Decompiler.Tests.TestCases.Ugly
+{
+	[Extension]
+	internal static class NoExtensionMethods
+	{
+		[Extension]
+		internal static Func<T> AsFunc<T>(T value) where T : class
+		{
+			return new Func<T>(value, __ldftn(Return));
+		}
+
+		[Extension]
+		private static T Return<T>(T value)
+		{
+			return value;
+		}
+	}
+}

ICSharpCode.Decompiler.Tests/TestCases/Ugly/NoExtensionMethods.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace ICSharpCode.Decompiler.Tests.TestCases.Ugly
+{
+	internal static class NoExtensionMethods
+	{
+		internal static Func<T> AsFunc<T>(this T value) where T : class
+		{
+			return new Func<T>(value.Return);
+		}
+
+		private static T Return<T>(this T value)
+		{
+			return value;
+		}
+	}
+}

ICSharpCode.Decompiler.Tests/TestCases/Ugly/NoExtensionMethods.opt.roslyn.il

@@ -0,0 +1,69 @@
+
+
+
+
+// Metadata version: v4.0.30319
+.assembly extern mscorlib
+{
+  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
+  .ver 4:0:0:0
+}
+.assembly NoExtensionMethods
+{
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
+                                                                                                             63 65 70 74 69 6F 6E 54 68 72 6F 77 73 01 )       // ceptionThrows.
+
+  // --- The following custom attribute is added automatically, do not uncomment -------
+  //  .custom instance void [mscorlib]System.Diagnostics.DebuggableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggableAttribute/DebuggingModes) = ( 01 00 02 00 00 00 00 00 ) 
+
+  .permissionset reqmin
+             = {[mscorlib]System.Security.Permissions.SecurityPermissionAttribute = {property bool 'SkipVerification' = bool(true)}}
+  .hash algorithm 0x00008004
+  .ver 0:0:0:0
+}
+.module NoExtensionMethods.dll
+.custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
+.imagebase 0x10000000
+.file alignment 0x00000200
+.stackreserve 0x00100000
+.subsystem 0x0003       // WINDOWS_CUI
+.corflags 0x00000001    //  ILONLY
+
+
+// =============== CLASS MEMBERS DECLARATION ===================
+
+.class private abstract auto ansi sealed beforefieldinit ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods
+       extends [mscorlib]System.Object
+{
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+  .method assembly hidebysig static class [mscorlib]System.Func`1<!!T> 
+          AsFunc<class T>(!!T 'value') cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       18 (0x12)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  box        !!T
+    IL_0006:  ldftn      !!0 ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods::Return<!!0>(!!0)
+    IL_000c:  newobj     instance void class [mscorlib]System.Func`1<!!T>::.ctor(object,
+                                                                                 native int)
+    IL_0011:  ret
+  } // end of method NoExtensionMethods::AsFunc
+
+  .method private hidebysig static !!T  Return<T>(!!T 'value') cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       2 (0x2)
+    .maxstack  8
+    IL_0000:  ldarg.0
+    IL_0001:  ret
+  } // end of method NoExtensionMethods::Return
+
+} // end of class ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods
+
+
+// =============================================================
+
+// *********** DISASSEMBLY COMPLETE ***********************

ICSharpCode.Decompiler.Tests/TestCases/Ugly/NoExtensionMethods.roslyn.il

@@ -0,0 +1,81 @@
+
+
+
+
+// Metadata version: v4.0.30319
+.assembly extern mscorlib
+{
+  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
+  .ver 4:0:0:0
+}
+.assembly NoExtensionMethods
+{
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilationRelaxationsAttribute::.ctor(int32) = ( 01 00 08 00 00 00 00 00 ) 
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.RuntimeCompatibilityAttribute::.ctor() = ( 01 00 01 00 54 02 16 57 72 61 70 4E 6F 6E 45 78   // ....T..WrapNonEx
+                                                                                                             63 65 70 74 69 6F 6E 54 68 72 6F 77 73 01 )       // ceptionThrows.
+
+  // --- The following custom attribute is added automatically, do not uncomment -------
+  //  .custom instance void [mscorlib]System.Diagnostics.DebuggableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggableAttribute/DebuggingModes) = ( 01 00 07 01 00 00 00 00 ) 
+
+  .permissionset reqmin
+             = {[mscorlib]System.Security.Permissions.SecurityPermissionAttribute = {property bool 'SkipVerification' = bool(true)}}
+  .hash algorithm 0x00008004
+  .ver 0:0:0:0
+}
+.module NoExtensionMethods.dll
+.custom instance void [mscorlib]System.Security.UnverifiableCodeAttribute::.ctor() = ( 01 00 00 00 ) 
+.imagebase 0x10000000
+.file alignment 0x00000200
+.stackreserve 0x00100000
+.subsystem 0x0003       // WINDOWS_CUI
+.corflags 0x00000001    //  ILONLY
+
+
+// =============== CLASS MEMBERS DECLARATION ===================
+
+.class private abstract auto ansi sealed beforefieldinit ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods
+       extends [mscorlib]System.Object
+{
+  .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+  .method assembly hidebysig static class [mscorlib]System.Func`1<!!T> 
+          AsFunc<class T>(!!T 'value') cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       23 (0x17)
+    .maxstack  2
+    .locals init (class [mscorlib]System.Func`1<!!T> V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  box        !!T
+    IL_0007:  ldftn      !!0 ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods::Return<!!0>(!!0)
+    IL_000d:  newobj     instance void class [mscorlib]System.Func`1<!!T>::.ctor(object,
+                                                                                 native int)
+    IL_0012:  stloc.0
+    IL_0013:  br.s       IL_0015
+
+    IL_0015:  ldloc.0
+    IL_0016:  ret
+  } // end of method NoExtensionMethods::AsFunc
+
+  .method private hidebysig static !!T  Return<T>(!!T 'value') cil managed
+  {
+    .custom instance void [mscorlib]System.Runtime.CompilerServices.ExtensionAttribute::.ctor() = ( 01 00 00 00 ) 
+    // Code size       7 (0x7)
+    .maxstack  1
+    .locals init (!!T V_0)
+    IL_0000:  nop
+    IL_0001:  ldarg.0
+    IL_0002:  stloc.0
+    IL_0003:  br.s       IL_0005
+
+    IL_0005:  ldloc.0
+    IL_0006:  ret
+  } // end of method NoExtensionMethods::Return
+
+} // end of class ICSharpCode.Decompiler.Tests.TestCases.Ugly.NoExtensionMethods
+
+
+// =============================================================
+
+// *********** DISASSEMBLY COMPLETE ***********************

ICSharpCode.Decompiler.Tests/UglyTestRunner.cs

@@ -83,6 +83,14 @@ namespace ICSharpCode.Decompiler.Tests
 			});
 		}
 
+		[Test]
+		public void NoExtensionMethods([ValueSource("roslynOnlyOptions")] CompilerOptions cscOptions)
+		{
+			RunForLibrary(cscOptions: cscOptions, decompilerSettings: new DecompilerSettings {
+				ExtensionMethods = false
+			});
+		}
+
 		void RunForLibrary([CallerMemberName] string testName = null, AssemblerOptions asmOptions = AssemblerOptions.None, CompilerOptions cscOptions = CompilerOptions.None, DecompilerSettings decompilerSettings = null)
 		{
 			Run(testName, asmOptions | AssemblerOptions.Library, cscOptions | CompilerOptions.Library, decompilerSettings);

ICSharpCode.Decompiler/CSharp/CallBuilder.cs

@@ -1235,6 +1235,11 @@ namespace ICSharpCode.Decompiler.CSharp
 				default:
 					throw new ArgumentException($"Unknown instruction type: {func.OpCode}");
 			}
+			if (method.IsStatic  && !method.IsExtensionMethod) {
+				var argumentList = BuildArgumentList(expectedTargetDetails, null, inst.Method,
+					0, inst.Arguments, null);
+				return HandleConstructorCall(new ExpectedTargetDetails { CallOpCode = OpCode.NewObj }, null, inst.Method, argumentList).WithILInstruction(inst);
+			}
 			return HandleDelegateConstruction(inst.Method.DeclaringType, method, expectedTargetDetails, thisArg, inst);
 		}
 
@@ -1243,9 +1248,15 @@ namespace ICSharpCode.Decompiler.CSharp
 			return HandleDelegateConstruction(inst.Type, inst.Method, new ExpectedTargetDetails { CallOpCode = OpCode.CallVirt }, inst.Argument, inst);
 		}
 
-		TranslatedExpression HandleDelegateConstruction(IType delegateType, IMethod method, ExpectedTargetDetails expectedTargetDetails, ILInstruction thisArg, ILInstruction inst)
+		internal ExpressionWithResolveResult BuildMethodReference(IMethod method, bool isVirtual)
+		{
+			var expr = BuildDelegateReference(method, invokeMethod: null, new ExpectedTargetDetails { CallOpCode = isVirtual ? OpCode.CallVirt : OpCode.Call }, thisArg: null);
+			expr.Expression.RemoveAnnotations<ResolveResult>();
+			return expr.Expression.WithRR(new MemberResolveResult(null, method));
+		}
+
+		ExpressionWithResolveResult BuildDelegateReference(IMethod method, IMethod invokeMethod, ExpectedTargetDetails expectedTargetDetails, ILInstruction thisArg)
 		{
-			var invokeMethod = delegateType.GetDelegateInvokeMethod();
 			TranslatedExpression target;
 			IType targetType;
 			bool requireTarget;
@@ -1331,27 +1342,32 @@ namespace ICSharpCode.Decompiler.CSharp
 				}
 			}
 			requireTarget = !method.IsLocalFunction && (step & 1) != 0;
-			Expression targetExpression;
+			ExpressionWithResolveResult targetExpression;
 			Debug.Assert(result != null);
 			if (requireTarget) {
 				Debug.Assert(target.Expression != null);
 				var mre = new MemberReferenceExpression(target, methodName);
 				if ((step & 2) != 0)
 					mre.TypeArguments.AddRange(method.TypeArguments.Select(expressionBuilder.ConvertType));
-				mre.WithRR(result);
-				targetExpression = mre;
+				targetExpression = mre.WithRR(result);
 			} else {
 				var ide = new IdentifierExpression(methodName);
 				if ((step & 2) != 0)
 					ide.TypeArguments.AddRange(method.TypeArguments.Select(expressionBuilder.ConvertType));
-				ide.WithRR(result);
-				targetExpression = ide;
+				targetExpression = ide.WithRR(result);
 			}
+			return targetExpression;
+		}
+
+		TranslatedExpression HandleDelegateConstruction(IType delegateType, IMethod method, ExpectedTargetDetails expectedTargetDetails, ILInstruction thisArg, ILInstruction inst)
+		{
+			var invokeMethod = delegateType.GetDelegateInvokeMethod();
+			var targetExpression = BuildDelegateReference(method, invokeMethod, expectedTargetDetails, thisArg);
 			var oce = new ObjectCreateExpression(expressionBuilder.ConvertType(delegateType), targetExpression)
 				.WithILInstruction(inst)
 				.WithRR(new ConversionResolveResult(
 					delegateType,
-					result,
+					targetExpression.ResolveResult,
 					Conversion.MethodGroupConversion(method, expectedTargetDetails.CallOpCode == OpCode.CallVirt, false)));
 			return oce;
 		}

ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs

@@ -3134,6 +3134,22 @@ namespace ICSharpCode.Decompiler.CSharp
 				.WithRR(new OperatorResolveResult(SpecialType.Dynamic, inst.Operation, new[] { target.ResolveResult, value.ResolveResult }));
 		}
 
+		protected internal override TranslatedExpression VisitLdFtn(LdFtn inst, TranslationContext context)
+		{
+			ExpressionWithResolveResult delegateRef = new CallBuilder(this, typeSystem, settings).BuildMethodReference(inst.Method, isVirtual: false);
+			return new InvocationExpression(new IdentifierExpression("__ldftn"), delegateRef)
+				.WithRR(new ResolveResult(compilation.FindType(KnownTypeCode.IntPtr)))
+				.WithILInstruction(inst);
+		}
+
+		protected internal override TranslatedExpression VisitLdVirtFtn(LdVirtFtn inst, TranslationContext context)
+		{
+			ExpressionWithResolveResult delegateRef = new CallBuilder(this, typeSystem, settings).BuildMethodReference(inst.Method, isVirtual: true);
+			return new InvocationExpression(new IdentifierExpression("__ldvirtftn"), delegateRef)
+				.WithRR(new ResolveResult(compilation.FindType(KnownTypeCode.IntPtr)))
+				.WithILInstruction(inst);
+		}
+
 		protected internal override TranslatedExpression VisitInvalidBranch(InvalidBranch inst, TranslationContext context)
 		{
 			string message = "Error";